Question: Simplify the following expression: $t = \dfrac{1}{3z} - \dfrac{1}{2z}$
Answer: In order to subtract expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $3z$ and $2z$ $\lcm(3z, 2z) = 6z$ $ t = \dfrac{2}{2} \cdot \dfrac{1}{3z} - \dfrac{3}{3} \cdot \dfrac{1}{2z} $ $t = \dfrac{2}{6z} - \dfrac{3}{6z}$ $t = \dfrac{2 -3}{6z}$ $t = \dfrac{-1}{6z}$